View Javadoc

1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.impl.nio.codecs;
29  
30  import java.io.IOException;
31  import java.nio.ByteBuffer;
32  import java.nio.channels.FileChannel;
33  import java.nio.channels.ReadableByteChannel;
34  
35  import org.apache.http.annotation.NotThreadSafe;
36  import org.apache.http.impl.io.HttpTransportMetricsImpl;
37  import org.apache.http.nio.FileContentDecoder;
38  import org.apache.http.nio.reactor.SessionInputBuffer;
39  
40  /**
41   * Content decoder that reads data without any transformation. The end of the
42   * content entity is delineated by closing the underlying connection
43   * (EOF condition). Entities transferred using this input stream can be of
44   * unlimited length.
45   * <p>
46   * This decoder is optimized to transfer data directly from the underlying
47   * I/O session's channel to a {@link FileChannel}, whenever
48   * possible avoiding intermediate buffering in the session buffer.
49   *
50   * @since 4.0
51   */
52  @NotThreadSafe
53  public class IdentityDecoder extends AbstractContentDecoder
54          implements FileContentDecoder {
55  
56      public IdentityDecoder(
57              final ReadableByteChannel channel,
58              final SessionInputBuffer buffer,
59              final HttpTransportMetricsImpl metrics) {
60          super(channel, buffer, metrics);
61      }
62  
63      /**
64       * Sets the completed status of this decoder. Normally this is not necessary
65       * (the decoder will automatically complete when the underlying channel
66       * returns EOF). It is useful to mark the decoder as completed if you have
67       * some other means to know all the necessary data has been read and want to
68       * reuse the underlying connection for more messages.
69       */
70      public void setCompleted(boolean completed) {
71          this.completed = completed;
72      }
73  
74      public int read(final ByteBuffer dst) throws IOException {
75          if (dst == null) {
76              throw new IllegalArgumentException("Byte buffer may not be null");
77          }
78          if (this.completed) {
79              return -1;
80          }
81  
82          int bytesRead;
83          if (this.buffer.hasData()) {
84              bytesRead = this.buffer.read(dst);
85          } else {
86              bytesRead = this.channel.read(dst);
87              if (bytesRead > 0) {
88                  this.metrics.incrementBytesTransferred(bytesRead);
89              }
90          }
91          if (bytesRead == -1) {
92              this.completed = true;
93          }
94          return bytesRead;
95      }
96  
97      public long transfer(
98              final FileChannel dst,
99              long position,
100             long count) throws IOException {
101 
102         if (dst == null) {
103             return 0;
104         }
105         if (this.completed) {
106             return 0;
107         }
108 
109         long bytesRead;
110         if (this.buffer.hasData()) {
111             dst.position(position);
112             bytesRead = this.buffer.read(dst);
113         } else {
114             if (this.channel.isOpen()) {
115                 if (position > dst.size()) {
116                     throw new IOException("Position past end of file [" + position +
117                             " > " + dst.size() + "]");
118                 }
119                 bytesRead = dst.transferFrom(this.channel, position, count);
120                 if (count > 0 && bytesRead == 0) {
121                     bytesRead = this.buffer.fill(this.channel);
122                 }
123             } else {
124                 bytesRead = -1;
125             }
126             if (bytesRead > 0) {
127                 this.metrics.incrementBytesTransferred(bytesRead);
128             }
129         }
130         if (bytesRead == -1) {
131             this.completed = true;
132         }
133         return bytesRead;
134     }
135 
136     @Override
137     public String toString() {
138         StringBuilder buffer = new StringBuilder();
139         buffer.append("[identity; completed: ");
140         buffer.append(this.completed);
141         buffer.append("]");
142         return buffer.toString();
143     }
144 
145 }